medium

2 min read

Wait notify

Wait Notify A wait notify is a mechanism used to synchronize multiple threads when one thread needs to wait for a specific event or operation to complete. T...

Wait Notify

A wait notify is a mechanism used to synchronize multiple threads when one thread needs to wait for a specific event or operation to complete. This allows the other threads to continue executing without being blocked indefinitely.

How it works:

One thread, the notifying thread, sets a flag or executes an operation that indicates the event or operation will happen.
Another thread, the waiting thread, blocks its execution until it detects the flag or receives a notification.
Once the waiting thread detects the event, it releases the notifying thread and continues its execution.

Example:

Imagine two threads:

Thread A: This thread wants to wait for a new message to arrive in a chat window.
Thread B: This thread is responsible for sending the message.

Here's an example of wait notify:

java

public class Example {

private boolean notified = false;

public void threadA() {

// Set the flag to indicate that a message is received

notified = true;

// Perform some operations that depend on the message

System.out.println("Received a message!");

}

public void threadB() {

// Block execution until the notifying thread sets the flag

while (!notified) {

// Perform some waiting operations

}

// Process the message and complete the operation

System.out.println("Processing the message...");

}

Benefits of using wait notify:

Efficiently synchronize multiple threads
Prevent thread blocking and maintain responsiveness
Allow other threads to continue executing while waiting

Note:

The notifying thread needs to explicitly set the flag or notify the waiting thread through an external mechanism (e.g., a message queue, event listener).
The waiting thread should be designed to handle blocking operations gracefully and avoid becoming stuck